According to ChannelWeb a federal judge sitting in the US Court of Appeals has ruled that open source software licenses are . This is a complete u-turn on a previous ruling which had thrown the not so small matter of open source licensing into something of a legal quagmire.
The case appears to have arisen out of a dispute, of all things, over the legality of an open source license for model railway control software after a developer gave another an 'artistic license' and that other then used it while developing a competing product.
Earlier, a court had decided that there was no violation of copyright law in the case, but rather it was a matter of contractual promise more than anything.
The higher court did not agree and has stated "copyright holders who engage in open source licensing have the right to control the modification and distribution of copyrighted material."